Lithium batteries are the preferred energy source in various applications due to their energy density, power, and shelf life characteristics. Examples of lithium batteries include non-aqueous batteries such as lithium-ion and lithium polymer batteries.
A separator between positive and negative electrodes of a conventional lithium battery constitutes an important component of the battery. Separators for conventional, planar lithium-ion batteries are typically solid micro-porous polyolefin films that are assembled in a sheet form and rolled in the form of a cathode/separator/anode/separator stack. This stack is rolled tightly and inserted into a can, filled with electrolyte, and then sealed. For example, reference to P. Arora and Z. Zhang, “Battery separators,” Chem. Rev., 2004, 104, 4419-4462, may help to illustrate the state of the art in battery separators, and is therefore incorporated by reference as non-essential subject matter herein.
Three-dimensional battery architectures (e.g., interdigitated electrode arrays) have been proposed in the literature to provide higher electrode surface area, higher energy and power density, improved battery capacity, and improved active material utilization compared with two-dimensional architectures (e.g., flat and spiral laminates). For example, reference to Long et. al., “Three-dimensional battery architectures,” Chemical Reviews, 2004, 104, 4463-4492, may help to illustrate the state of the art in proposed three-dimensional battery architectures, and is therefore incorporated by reference as non-essential subject matter herein. FIG. 1 shows a schematic representation of a cross-section of one example of a three-dimensional battery that has been proposed in the literature. The battery includes a cathode current collector 10 from which cathodes 11 extend into a height direction at various points. A similar structure is made with an anode current collector 14 and anodes 13. The regions between the cathodes 11 and the anodes 13 (and some areas of the current collectors 10 and 14) include electrolyte 12.
The cathodes 11 and anodes 13 may be assembled in various three-dimensional configurations. This can include, for example, inter-digitated pillars or plates where the anodes 13 and the cathodes 11 are in proximity to each other in more than one direction. For example, in FIG. 1, each anode 13 is in close proximity to two cathodes 11, one on either side. In structures such as pillars, each electrode could be in proximity to surfaces from more than 2 counter electrodes. The anode and cathode current collectors 10 and 14 can be separate (top and bottom connection as shown in FIG. 1) or co-planar.
An improved method for incorporating a separator in a three-dimensional lithium battery is desirable in the art.